Commercial 

Airplanes 757

Service Bulletin

SPECIAL ATTENTION

Number: 757-28-0121

Original Issue: August 18, 2010

ATA System: 2841

SUBJECT: FUEL-Fuel Quantity Indicating System (FQIS)- Fuel Quantity Processor Unit, Low Fuel

Quantity Indication Test

Export of this technology is controlled under the United States Export Administration Regulations (EAR) (15

CFR 730-774). An export license may be required before it is used for development, production or use by foreign

persons from specific countries. The controller of this data has the individual responsibility to abide by all export

laws.

ECCN: 9E991

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Copyright © 2010 The Boeing Company

Unpublished Work - All Rights Reserved

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subject matter. Boeing also claims copyright in this document as a compilation and/or collective work.

This document includes proprietary information owned by The Boeing Company and/or one or more third parties.

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Boeing, the Boeing signature, the Boeing symbol, 707, 717, 727, 737, 747, 757, 767, 777, 787, Dreamliner,

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BLANK PAGE
Table of Contents

Summary ...................................................... 5

1. PLANNING INFORMATION ........................................ 9

A. Effectivity ................................................ 9

1. Airplanes ............................................. 9

2. Spares Affected . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

B. Concurrent Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

C. Reason . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

D. Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

E. Compliance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

F. Approval . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

G. Manpower . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

H. Weight and Balance Changes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

I. Electrical Load Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

J. References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

1. Existing Data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

2. Data supplied with this Service Bulletin . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

3. Installation Drawings Used in the Preparation of this Service Bulletin . . . . . . . . . . . . 15

K. Publications Affected . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

L. Interchangeability and Intermixability of Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

2. MATERIAL INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

A. Material - Price and Availability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

B. Industry Support Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

C. Parts Necessary For Each Airplane . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

1. Kits/Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

2. Parts and Materials Supplied by the Operator . . . . . . . . . . . . . . . . . . . . . . . . 17

3. Parts Modified and Reidentified . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

4. Parts Removed and Not Replaced . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

D. Parts Necessary to Change Spares . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

E. Special Tooling - Price and Availability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

F. Special Tooling Necessary to do this Service Bulletin . . . . . . . . . . . . . . . . . . . . . . . 17

3. ACCOMPLISHMENT INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

A. GENERAL INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

B. WORK INSTRUCTIONS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

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Commercial 

Airplanes 757

Service Bulletin

SPECIAL ATTENTION

Summary Number: 757-28-0121

Original Issue: August 18, 2010

ATA System: 2841

SUBJECT: FUEL-Fuel Quantity Indicating System (FQIS)- Fuel Quantity Processor Unit, Low Fuel

Quantity Indication Test

BOEING RECOMMENDS THAT EACH OPERATOR EXAMINE THIS SERVICE BULLETIN IMMEDIATELY.

CONCURRENT REQUIREMENTS

None.

BACKGROUND

This service bulletin provides test procedures to make sure that the Engine Indication and Crew Alerting System

(EICAS) receives both, the LOW FUEL and the FUEL CONFIG discrete signals from the Fuel Quantity Processor

Unit (FQPU), and the Fuel Quantity Indicating System (FQIS), is functioning correctly. If this service bulletin is

not incorporated flight crews may be unaware of low fuel situations that can lead to fuel exhaustion and extreme

emergency measures.

A 757-200 operator reported that the Low Fuel Indicating System failed to alert the flight crew that the fuel in

Left Hand (LH) and Right Hand (RH) main tanks were depleted below the minimum 2,200 lbs in either tank. The

Low Fuel Threshold is 2,200 lbs of fuel for either Main Fuel Tank. When the fuel in either LH or RH main tank

is below 2,200 lbs, the EICAS should receive both the LOW FUEL and FUEL CONFIG discrete signals from the

FQPU in order for EICAS to display the LOW FUEL caution message.

The Operator reported to Boeing that the airplane arrived at it’s destination with main tank fuel levels below the

Low Fuel Threshold. The next flight crew reported 8,000 lbs of fuel in the Center Wing Tank (CWT), 1,800 lbs

of fuel in the Right Hand Main Fuel Tank and 1,400 lbs of fuel in the Left Hand Main Fuel tank.

Boeing determined this to be a safety issue. Operators can expect to eliminate similar safety incidents by doing

the interval tests in accordance with this service bulletin.

757/767-SRP-28-0124 is related to this service bulletin.

ACTION

Test the Low Fuel Quantity Indicating System to make sure that the, Low Fuel Indication, and the Fuel

Configuration indication are functioning correctly.

Make sure the EICAS displays the "LOW FUEL" caution message and the "FUEL CONFIG" light on the Pilots

Overhead Panel (P5 Panel) comes "ON".

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If the test fails troubleshoot for wiring faults, bent connector pins, or damaged equipment. Repair or replace

damaged wires or equipment.

EFFECTIVITY

757-200/-200CB/-200PF/-300 Airplanes line numbers 1 through 1050. Refer to Paragraph 1.A.1., Airplanes, for

the list of affected airplanes.

COMPLIANCE

The Federal Aviation Administration (FAA) will possibly release an Airworthiness Directive related to this service

bulletin. The Airworthiness Directive will make the compliance tasks and times given in this service bulletin

mandatory.

Boeing recommends that the Inspection/Interval Test given in this service bulletin be done every 100 flight hours.

INDUSTRY SUPPORT INFORMATION

Boeing warranty remedies are not available for the Inspection/Interval Test given in this service bulletin.

MANPOWER

Refer to Paragraph 1.G., Manpower.

MATERIAL INFORMATION

None.

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BLANK PAGE
Commercial 

Airplanes 757

Service Bulletin

SPECIAL ATTENTION

Number: 757-28-0121

Original Issue: August 18, 2010

ATA System: 2841

SUBJECT: FUEL-Fuel Quantity Indicating System (FQIS)- Fuel Quantity Processor Unit, Low Fuel

Quantity Indication Test

BOEING RECOMMENDS THAT EACH OPERATOR EXAMINE THIS SERVICE BULLETIN IMMEDIATELY.

1. PLANNING INFORMATION

A. Effectivity

1. Airplanes

This service bulletin is for the airplanes shown below.

Refer to Service Bulletin Index Document D624N001 Part 3 for Airplane Variable Number, Line

Number, and Serial Number data.

GROUP CONFIGURATION DESCRIPTION

1 - 757-200/-200CB/-200PF/-300 Airplanes line numbers 1 to 1050.

Airplane Models:

757-200, 757-200CB, 757-200PF, 757-300

Variable Number Group

NA001 - NA028 1

NA191 - NA199 1

NA201 - NA239 1

NA301 - NA305 1

NA341 - NA352 1

NA391 - NA399 1

NA401 - NA408 1

NA441 - NA447 1

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Variable Number Group

NA501 - NA586 1

NB001 - NB004 1

NB021 - NB023 1

NB036 - NB041 1

NB051 - NB053 1

NB061 - NB073 1

NB079 1

NB131 - NB148 1

NB161 - NB162 1

NB166 - NB168 1

NB201 - NB204 1

NB221 - NB228 1

NB230 1

NB236 1

NB239 1

NB261 - NB267 1

NB291 - NB299 1

NB301 - NB302 1

NB311 - NB312 1

NB321 - NB331 1

NB421 - NB438 1

NB446 1

NB451 - NB454 1

NB501 - NB523 1

NB561 1

NB571 1

NB581 - NB583 1

NC001 - NC033 1

NC041 - NC042 1

NC051 - NC052 1

NC056 - NC062 1

NC066 - NC084 1

NC091 - NC094 1

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BOEING SERVICE BULLETIN 757-28-0121
Variable Number Group

NC151 1

NC161 1

NC901 - NC951 1

NC971 - NC974 1

ND001 - ND007 1

ND011 - ND059 1

ND111 - ND113 1

ND161 - ND199 1

ND201 - ND203 1

ND221 - ND225 1

ND241 - ND248 1

ND301 - ND322 1

ND401 1

ND891 1

ND895 1

NE001 - NE008 1

NE011 - NE088 1

NE091 - NE094 1

NE141 - NE150 1

NE161 - NE177 1

NE201 - NE204 1

NE301 - NE302 1

NE311 - NE325 1

NJ001 - NJ004 1

NJ031 - NJ032 1

NJ551 - NJ555 1

NL001 - NL002 1

NL006 - NL017 1

NL101 - NL109 1

NL141 1

NL601 - NL616 1

NN001 - NN002 1

NN051 - NN052 1

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BOEING SERVICE BULLETIN 757-28-0121
Variable Number Group

NP901 - NP904 1

NS601 - NS616 1

NT001 - NT009 1

NT201 - NT202 1

NT231 - NT234 1

NT237 - NT240 1

NT242 1

NT245 - NT248 1

NT281 - NT289 1

NT341 - NT347 1

NT351 - NT360 1

NT371 - NT373 1

NT375 - NT379 1

NT381 - NT386 1

NT401 - NT409 1

NT411 - NT412 1

NT426 - NT427 1

NT431 - NT432 1

NT436 - NT438 1

NT441 - NT442 1

NT446 1

NT701 - NT769 1

NT791 - NT796 1

NT861 - NT862 1

NT881 - NT885 1

NT901 - NT916 1

NT971 - NT985 1

NU031 - NU038 1

NU701 - NU705 1

NU721 - NU728 1

NU731 - NU732 1

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BOEING SERVICE BULLETIN 757-28-0121
2. Spares Affected

None.

B. Concurrent Requirements

None.

C. Reason

This service bulletin provides test procedures to make sure that the Engine Indication and Crew Alerting

System (EICAS) receives both, the LOW FUEL and the FUEL CONFIG discrete signals from the Fuel

Quantity Processor Unit (FQPU), and the Fuel Quantity Indicating System (FQIS), is functioning correctly.

If this service bulletin is not incorporated flight crews may be unaware of low fuel situations that can

lead to fuel exhaustion and extreme emergency measures.

A 757-200 operator reported that the Low Fuel Indicating System failed to alert the flight crew that the

fuel in Left Hand (LH) and Right Hand (RH) main tanks were depleted below the minimum 2,200 lbs

in either tank. The Low Fuel Threshold is 2,200 lbs of fuel for either Main Fuel Tank. When the fuel in

either LH or RH main tank is below 2,200 lbs, the EICAS should receive both the LOW FUEL and FUEL

CONFIG discrete signals from the FQPU in order for EICAS to display the LOW FUEL caution message.

The Operator reported to Boeing that the airplane arrived at it’s destination with main tank fuel levels

below the Low Fuel Threshold. The next flight crew reported 8,000 lbs of fuel in the Center Wing Tank

(CWT), 1,800 lbs of fuel in the Right Hand Main Fuel Tank and 1,400 lbs of fuel in the Left Hand Main

Fuel tank.

Boeing determined this to be a safety issue. Operators can expect to eliminate similar safety incidents

by doing the interval tests in accordance with this service bulletin.

757/767-SRP-28-0124 is related to this service bulletin.

D. Description

Test the Low Fuel Quantity Indicating System to make sure that the, Low Fuel Indication, and the Fuel

Configuration indication are functioning correctly.

Make sure the EICAS displays the "LOW FUEL" caution message and the "FUEL CONFIG" light on

the Pilots Overhead Panel (P5 Panel) comes "ON".

If the test fails troubleshoot for wiring faults, bent connector pins, or damaged equipment. Repair or

replace damaged wires or equipment.

The work in this service bulletin is done in the maintenance zone(s) given below.

Affected Maintenance Zones

Model Zone

757-200, 757-200CB, 757- 119, 121, 122, 211, 212, 221, 222

200PF, 757-300

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BOEING SERVICE BULLETIN 757-28-0121
E. Compliance

The Federal Aviation Administration (FAA) will possibly release an Airworthiness Directive related to

this service bulletin. The Airworthiness Directive will make the compliance tasks and times given in this

service bulletin mandatory.

Boeing recommends that the inspection/Interval Test given in this service bulletin be done every 100

flight hours.

F. Approval

This service bulletin was examined by the Federal Aviation Administration (FAA). The changes specified

in this service bulletin comply with the applicable regulations and are FAA approved, as well as European

Aviation Safety Agency (EASA)/Joint Aviation Authorities (JAA) approved for all EASA/JAA approved

airplanes listed in the service bulletin effectivity. This service bulletin and its approval were based on

the airplane in its original Boeing delivery configuration or as modified by other approved Boeing

changes.

If an airplane has a non-Boeing modification or repair that affects a component or system also affected

by this service bulletin, the operator is responsible for obtaining appropriate regulatory agency approval

before incorporating this service bulletin.

G. Manpower

The table below shows an estimate of the task hours necessary to do this for each . This estimate is

for direct labor only, done by an experienced crew. Adjust the estimate with operator task hour data if

necessary. The estimate does not include lost time. These are some examples of lost time:

• Time to adjust to the workplace

• Time to schedule the work

• Time to inspect the work

• Time to cure the materials

• Time to make the parts

• Time to find the tools.

Task Number of Persons Task Hours Elapsed Hours

Open Access 1 0.25 0.25

Test 1 0.50 0.50

Close Access 1 0.25 0.25

TOTAL FOR EACH AIRPLANE 1.00 1.00

H. Weight and Balance Changes

None.

I. Electrical Load Data

Not changed.

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BOEING SERVICE BULLETIN 757-28-0121
J. References

1. Existing Data

a. Standard Wiring Practices Manual (SWPM) 20-10-11, 20-10-12, 20-10-19

b. 757 Aircraft Maintenance Manual (AMM) 24-22-00

c. 757 Fault Isolation Manual (FIM) 28-41-00

d. 757 Wiring Diagram Manual (WDM) 28-41-13

2. Data supplied with this Service Bulletin

None.

3. Installation Drawings Used in the Preparation of this Service Bulletin

K. Publications Affected

1. Publications:

None.

2. Damage Tolerance Based Structural Inspections:

Boeing has evaluated the repairs and/or changes in this service bulletin for effects on Fatigue

Critical Structure (FCS) and for changes to Damage Tolerance Inspections (DTI) required in the

Maintenance Program. This service bulletin does not affect FCS, therefore DTIs are not necessary.

L. Interchangeability and Intermixability of Parts

Accomplishment of this service bulletin does not affect interchangeability or intermixability of parts.

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2. MATERIAL INFORMATION

A. Material - Price and Availability

None.

B. Industry Support Information

Boeing warranty remedies are not available for the Inspection/Interval Test given in this service bulletin.

C. Parts Necessary For Each Airplane

1. Kits/Parts

None.

2. Parts and Materials Supplied by the Operator

None.

3. Parts Modified and Reidentified

None.

4. Parts Removed and Not Replaced

None.

D. Parts Necessary to Change Spares

None.

E. Special Tooling - Price and Availability

None.

F. Special Tooling Necessary to do this Service Bulletin

No special tools or equipment are necessary to do the change in this service bulletin. But, maintenance

and overhaul tools in the manuals given in Paragraph 1.J., References, can be necessary. Examine

operator tool supply to make sure all necessary tools are available.

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3. ACCOMPLISHMENT INSTRUCTIONS

A. GENERAL INFORMATION

CAUTION: KEEP THE WORK AREA, WIRES AND ELECTRICAL BUNDLES CLEAN OF METAL

PARTICLES OR CONTAMINATION WHEN YOU USE TOOLS. UNWANTED MATERIAL,

METAL PARTICLES OR CONTAMINATION CAUGHT IN WIRE BUNDLES CAN CAUSE

DAMAGE TO THE BUNDLES. DAMAGED WIRE BUNDLES CAN CAUSE SPARKS OR

OTHER ELECTRICAL DAMAGE.

NOTE: 1. The instructions identified in Paragraph 3.B., Work Instructions, and the Figure(s)

give the recommended sequence of steps. The sequence of steps to do this service

bulletin can be changed.

2. Manual titles are referred to by acronyms. Refer to Paragraph 1.J., References, for

definition of the acronyms.

3. Obey all of the warnings and cautions given in the specified manual sections.

4. Refer to the SWPM 20-10-11 and SWPM 20-10-12 for the wire installation procedures,

and SWPM 20-10-19 for the wire separation requirements, as accepted procedures.

5. A Detailed Inspection is defined as: An intensive examination of a specific item,

installation, or assembly to detect damage, failure, or irregularity. Available lighting

is normally supplemented with a direct source of good lighting at an intensity deemed

appropriate. Inspection aids such as mirrors, magnifying lenses, etc. may be

necessary. Surface cleaning and elaborate procedures may be required.

6. A General Visual Inspection is defined as: A visual examination of an interior or

exterior area, installation or assembly to detect obvious damage, failure or irregularity.

This level of inspection is made from within touching distance unless otherwise

specified. A mirror may be necessary to enhance visual access to all exposed surfaces

in the inspection area. This level of inspection is made under normally available

lighting conditions such as daylight, hangar lighting, flashlight or drop-light and may

require removal or opening of access panels or doors. Stands, ladders or platforms

may be required to gain proximity to the area being checked.

7. These work instructions refer to procedures included in other Boeing documents.

When the words "refer to" are used and the operator has an accepted alternative

procedure, the accepted alternative procedure can be used. When the words "in

accordance with" are included in the instruction, the procedure in the Boeing document

must be used.

B. WORK INSTRUCTIONS

1. Supply electrical power. Refer to 757 AMM 24-22-00 as an accepted procedure.

2. Make sure the following six EICAS circuit breakers are closed.

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BOEING SERVICE BULLETIN 757-28-0121
EICAS CIRCUIT BREAKERS, P11 PANEL

CIRCUIT NAME PANEL LOCATION

BREAKER

C4078 EICAS CMPTR L P11-3 J2

C4079 EICAS CMPTR R P11-4 J29

C4094 EICAS PILOTS DSP P11-4 J32

C4189 EICAS DISPLAY SW P11-4 J31

C4082 EICAS LOWER IND P11-4 J30

C4081 EICAS UPPER IND P11-3 J3

3. Push the MASTER CAUTION Cancel button on the P1-3, Captain Instrument Panel, Center to

reset warnings.

4. Push and release the FUEL QTY test switch on the Miscellaneous Test Panel (M10398), P61

Panel, to the FUEL QTY position.

a. Make sure the FUEL CONFIG light on the P5, Pilot's Overhead Panel, comes on.

b. Make sure the EICAS caution message, LOW FUEL, shows on the upper (EICAS) display,

P1 Panel.

NOTE: If the test fails, trouble shoot for wire faults, bent connector pins, or damaged

equipment. Repair and or replace damaged wires and or equipment. Refer to Fault

Isolation Manual 757 FIM 28-41-00 as an accepted procedure and to Wire Diagram

Manual 757 WDM 28-41-13 for related wires.

5. Put the airplane back to a serviceable condition.

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